Flexible card with fingerprint sensor

ABSTRACT

A prelam layer for use in forming a laminated card includes a flexible circuit substrate; a fingerprint sensor disposed on the flexible circuit substrate, the fingerprint sensor having upper and bottom surfaces, the bottom surface of the fingerprint sensor being disposed on the substrate, an active layer of the fingerprint sensor disposed towards the upper surface of the fingerprint sensor; a first integrated circuit chip disposed on the substrate and having at least one lead electrically connected to the flexible circuit substrate; and an adapter flexible circuit electrically bonded to the active layer of the fingerprint sensor. The integrated circuit chip is adapted to communicate with the fingerprint sensor through the adapter flexible circuit.

FIELD OF THE INVENTION

The present disclosure relates to biometric sensors and moreparticularly to integration of biometric sensors chip sets on a card.

BACKGROUND OF THE INVENTION

Fingerprint sensing and matching is a reliable and widely used techniquefor personal identification or verification. In particular, a commonapproach to fingerprint identification involves scanning a samplefingerprint to obtain an image thereof and storing the image and/orunique characteristics of the fingerprint image. The characteristics ofa sample fingerprint may be compared to information for referencefingerprints already in a database to determine proper identification ofa person, such as for verification purposes.

One class of fingerprint sensors is based on the active thermal sensingprinciple as described in, for example, U.S. Pat. No. 6,091,837 entitled“Sensor For Acquiring a Fingerprint” issued Jul. 18, 2000 and U.S. Pat.No. 7,910,902 entitled “Apparatus for Fingerprint Sensing” issued Mar.22, 2011, the entirety of each of which is hereby incorporated byreference herein.

There are challenges for integrating a biometric fingerprint chipsetinto a biometric system on card (BSoC). One challenge is that the activeside of the fingerprint sensor must necessarily be oriented in theupward direction because direct contact with the finger is needed. Thisorientation necessitates the use of wire-bonding where electricalcontact to the active side is established by wires bonds. But wirebonding techniques have high cost, low yield, and reliabilitydisadvantages.

SUMMARY OF THE INVENTION

In embodiments, a prelam layer for use in forming a laminated card,includes a flexible circuit substrate; a fingerprint sensor disposed onthe flexible circuit substrate, the fingerprint sensor having upper andbottom surfaces, the bottom surface of the fingerprint sensor beingdisposed on the substrate, an active layer of the fingerprint sensordisposed towards the upper surface of the fingerprint sensor; a firstintegrated circuit chip disposed on the substrate and having at leastone lead electrically connected to the flexible circuit substrate; andan adapter flexible circuit electrically bonded to the active layer ofthe fingerprint sensor, wherein the integrated circuit chip is adaptedto communicate with the fingerprint sensor through the adapter flexiblecircuit.

In embodiments, a biometric system on card comprises at least one bottomlamination layer, and a prelam layer disposed over the at least onebottom lamination layer. The prelam layer comprises a flexible circuitsubstrate; a fingerprint sensor disposed on the flexible circuitsubstrate, the fingerprint sensor having upper and bottom surfaces, thebottom surface of the fingerprint sensor disposed on the substrate, anactive layer of the fingerprint sensor disposed towards the uppersurface of the fingerprint sensor; a first integrated circuit chipdisposed on the substrate and having at least one lead electricallyconnected to the flexible circuit substrate; and an adapter flexiblecircuit electrically bonded to the active layer of the fingerprintsensor, wherein the first integrated circuit chip is adapted tocommunicate with the fingerprint sensor through the adapter flexiblecircuit. The system on card has at least one top lamination layer, thetop lamination layer having a window formed therein overlying thefingerprint sensor.

In embodiments, a method of forming prelam layers for use in forminglaminated cards, includes the steps of: providing a flexible circuitsubstrate sheet having a plurality of areas corresponding to individualcards, each card area having: a fingerprint sensor disposed on theflexible circuit substrate sheet, the fingerprint sensor having upperand bottom surfaces, the bottom surface of the fingerprint sensordisposed on the substrate sheet, an active layer of the fingerprintsensor disposed towards the upper surface of the fingerprint sensor, anda first integrated circuit chip disposed on the flexible circuitsubstrate sheet; disposing an adapter flexible circuit sheet over theflexible circuit substrate sheet; electrically bonding the adapterflexible circuit sheet to the active layer of each fingerprint sensor;and after the bonding step, cutting the adapter flexible circuit sheetand flexible circuit substrate sheet into a plurality of individualprelam layers, each individual prelam layer comprising one or more ofthe plurality of areas corresponding to one or more of the individualcards. Each individual prelam layer has a respective flexible circuitsubstrate and adapter flexible circuit electrically bonded to theflexible circuit substrate, wherein the integrated circuit chip of eachindividual prelam layer is adapted to communicate with the fingerprintsensor of the each individual prelam layer through the respectiveadapter flexible circuit.

The above and other features of the present invention will be betterunderstood from the following detailed description of the preferredembodiments of the invention that is provided in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention, as well as other information pertinent to the disclosure, inwhich:

FIG. 1 shows an embodiment of an architecture for a biometric system oncard.

FIG. 2 is a partial cross-sectional view of a biometric system on card;

FIG. 3 illustrates an embodiment of a prelam layer for use inmanufacturing a biometric system on card.

FIG. 4 illustrates another embodiment of a prelam layer for use inmanufacturing a biometric system on card.

FIG. 5 illustrates another embodiment of a prelam layer for use inmanufacturing a biometric system on card.

FIG. 6 illustrates another embodiment of a prelam layer for use inmanufacturing a biometric system on card.

FIG. 7 is a cross-sectional view of an embodiment of a double-sidedadapter flexible printed circuit.

FIG. 8 illustrates an embodiment of prelam precursor sheet.

FIG. 9 illustrates an embodiment of an adapter flexible printed circuitsheet.

FIG. 10 illustrates an embodiment of a card having a large areafingerprint sensor.

DETAILED DESCRIPTION

This description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,” “above,”“below,” “up,” “down,” “top” and “bottom” as well as derivative thereof(e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected” and “interconnected,” referto a relationship wherein structures are secured or attached to oneanother either directly or indirectly through intervening structures, aswell as both movable or rigid attachments or relationships, unlessexpressly described otherwise. Likewise, terms concerning electrical“connections” and “coupling” refer to a relationship wherein componentscommunicate with one another electrically either directly or indirectlythrough intervening structures unless described otherwise.

A smart card, chip card, or integrated circuit card (ICC) is anypocket-sized card with embedded integrated circuits. Smart cards aretypically made of plastic, for example polyvinyl chloride orpolyethylene terephthalate based polyesters, acrylonitrile butadienestyrene or polycarbonate.

FIG. 1 shows one possible architecture for a BSoC 10. A fingerprintsensor 12 captures an image of a fingerprint under control of an imagecapture ASIC 16 through an analog interface 14. The image capture ASIC16 reads this image out and transfers it via an interface 18 (e.g., SPIor USB interface) to an embedded microcontroller unit (MCU) 20. The MCU20 processes the image, extracts features and generates a fingerprinttemplate, typically based on so-called “minutiae”. In embodiments, suchas for smart credit card embodiments, the fingerprint template istransferred to a smart card chip 24 (integrated circuit card chip, ICC)where the match is performed in a so-called “match on chip” application.The MCU 20 may also be provided with fingerprint matching functionality.Fingerprint sensor modules comprising an imaging sensor, A/D converterASIC, and MCU with image processing, feature extraction, biometrictemplate generation, and biometric matcher are available commerciallyfrom NEXT Biometrics AS of Oslo, Norway under product designationNB-1411. Fingerprint sensor modules comprising an imaging sensor, A/Dconverter ASIC, and host interface (such as SPI or USB) are availablecommercially from NEXT Biometrics AS under product designation NB-1011.

In alternative embodiments, functionality of the image capture ASIC 16,MCU 20, and/or smart card chip 24 can be integrated into a single chipor chips. In alternative embodiments, the functionality of the sensor 12can be incorporated with the image capture ASIC 16 in one component andoptionally also with the functionality of the MCU 20 and/or smart cardchip 24.

FIG. 2 illustrates a partial cross-sectional view of a laminated BSoC50. The card 50 is formed from a prelam layer 52 (also referred to as a“core”), top lamination layer (or layers) 64 and bottom lamination layer(or layers) 62. By “prelam” it is meant a “prelaminated inlay” orlamination intermediate product for use during the production oflamination products (or other lamination intermediate products). The topand bottom lamination layers 62, 64, may be, for example, layers ofpolyvinyl chloride (PVC) or polyethylene terephthalate (PET) foil. Thelayers are laminated together under heat and/or pressure using processesfamiliar in the art of laminate card preparation. The prelam layer 52includes a flexible printed circuit substrate 54 having mounted thereona number of components, such as including the components described abovein connection with FIG. 1. In embodiments, the flexible printed circuitsubstrate material is PET with conductive copper traces for connectingthe mounted components to one another and/or to external interfaces. Theprelam flexible printed circuit substrate 54 can be very think, such asfor example around 80 μm in thickness. For purposes of illustration, theprelam layer 52 includes the fingerprint sensor 56 and an integratedcircuit chip 58 mounted to the flexible printed circuit substrate 54.The integrated circuit chip may be, for example, the image capture ASICdescribed above in connection with FIG. 1. The flexible printed circuitsubstrate 54 includes traces for making connections between thefingerprint sensor 56 and the integrated circuit chip 58 as well as withthe other components. The integrated circuit chip 58 is shown with itsactive side facing down (i.e., towards the substrate 54), withelectrical connections to the flexible printed circuit substrate layer52 made through conductive solder bumps 60. This connection technique isknown as flip chip.

In embodiments described herein, the integrated circuit chip 58 may be asmart card controller chip. In such embodiments, the image capturefunctionality may be integrated into the sensor 56, which may be asilicon based finger print sensor.

The fingerprint sensor 56 generally includes a substrate 56 b, which maybe a glass substrate, and an active layer 56 a formed thereover. Inembodiments the fingerprint sensor is a flexible sensor, assuming aflexible substrate 56 b such as a polysilicon substrate or thinnedsilicon substrate. In embodiments the sensor is a large area sensor suchas is part of the NB-0510-SP chipset manufactured by NEXT Biometrics ASof Oslo, Norway, which includes a sensor die on glass substrate and asmall package data capture ASIC responsible for A/D signal processing.These fingerprint sensors operate on the active thermal sensingprinciple, based on heat transfer. A low power heat pulse is applied toeach sensor pixel over a short period of time and a response ismeasured. This type of fingerprint sensor may be produced with largearea production processes such as low temperature polysilicon (LTPS)thin film transistors and devices. Sensor 56 may be secured to thesubstrate 54 using an adhesive or other suitable mechanical bondingtechnique. As can be seen in FIG. 2, a window 66 is formed in the toplaminate layer(s) 64 exposing the active layer 56 a of the sensor 56 atthe upper surface of the sensor. It should be understood that the activelayer 56 a could correspond to the upper surface of the sensor 56 or itcould be coated with an inactive layer or coating that permits imagetransfer. The active layer 56 a also includes lead areas for makingconnections to the active layer 56 a. When in use, a finger 70 islocated over and on the sensor 56. At present there are no mass producedflexible smartcards of this type with embedded large area sensors.Because the active layer 56 a of the sensor 56 must face upwards, wirebond connections 68, for example gold wires, must be used to connect theupper surface to the flexible printed circuit substrate 54. Not only dothese wire bond connections complicate the manufacturing process, butthey are not believed to be robust enough for use in a flexible card,which is subject to frequent bending stresses when used. And even ifwire-bonding is technically feasible, for mass-production given cost,yield, and reliability considerations, direct-contact bondingtechnologies, such as flip-chip soldering or anisotropic conductive film(ACF) are superior.

All elements of the card should be flexible. Smaller and thinnercomponents tend to be more flexible. Components such as the imageread-out ASIC 16, 58 can be thinned, for example to have a thicknessbetween or equal to about 120 μm and 450 μm, and bumped to allowsoldering. The dimensions of the ASIC 16 are around 3.5 mm×3.5 mm. Inembodiments, all components of biometric chipset on the card 50 canwithstand torsional bending stress as per ISO/IEC 10373-1. Rigidfingerprint sensors do not withstand torsional bending stress as perISO/IEC 10373-1 when integrated into a BSoC. This problem gets worse forlarge area sensors, e.g., sensors with a sense area of at least 169 mm².

In embodiments, the card 50 conforms with the standards for physicalcharacteristics for identification cards set forth in ISO/IEC 7810:2003Identification cards—Physical characteristics. In embodiments, theresulting card 50 is no larger than ID-1 size, as specified in ISO/IEC7810:2003. Credit cards are a common example of ISO/IEC 7810 ID-1 sizedcards. These cards have dimensions of 85.60×53.98 mm (3.370×2.125 in)and rounded corners with a radius of 2.88-3.48 mm. Other common examplesinclude ATM cards, debit cards, and drivers licenses in many countries.This format is also used for personal identity cards in some countries,for automated fare collection system cards for public transport, and forretail loyalty cards.

FIG. 10 illustrates a top view of ID-1 sized card 800 with embeddedfingerprint sensor 810 exposed through the top surface 805 of the card800. It should be understood that the top surface of the card may haveidentification information (e.g., photograph of the user and/or name),account information (e.g., credit card account information), brandinformation or any other information related to the use of the card.Likewise, the back surface of the card (not shown) may have a signatureblock, magnetic stripe and/or other information such as CVV number.

In embodiments, the card 50 conforms with the standards for physicalcharacteristics for biometric system on cards (BSoC) as defined in, forexample, ISO/IEC 17839-2 Biometric System-on-Card—Part 2: Physicalcharacteristics (draft standard). There is a relationship betweenfingerprint sensor area and the accuracy of the system, as measured byfalse match rates (FMR) and false non-match rates (FNMR). Whilesmaller-sized sensors are easier to integrate into a BSoC, these sensorsyield higher error rates. ISO/IEC 17839-2 Biometric System-on-Card givesa minimum area of 169 mm². The preferred sensor area is FederalInformation Processing Standards (FIPS) Fingerprint Acquisition Profile(FAP)-10 (12.7 mm×16.5 mm; specification PIV-071006), and morepreferably IPS FAP-20 (15.24 mm×20.32 mm; specification PIV-071006).

In embodiments, the height or thickness of the prelam layer of the card,including mounted components such as the fingerprint sensor, is betweenor equal to about 120-450 μm.

FIG. 3 illustrates an embodiment of a portion of a prelam layer 152 foruse in manufacturing a BSoC as described above. As with FIG. 2, theprelam layer includes a flexible printed circuit substrate 54 havingconductive traces for making connections between components (such asthose described above in connection with FIGS. 1 and 2). Large areabiometric sensor 56 is disposed on the flexible printed circuitsubstrate 54, with its active layer 56 a facing upwards. In thisembodiment, an adapter flexible circuit, for example a single sidedflexible printed circuit (FPC) 100, connects the active side 56 a ofsensor 56 to the flexible printed circuit substrate 54. The FPC 100 isbonded to the active layer 56 a of the sensor 56 by bonds 105 and to thesubstrate 54 by bonds 110. In embodiments, both bonds 105 and bonds 110are anisotropic conductive film (ACF) bonds ACF bonding is an epoxyadhesive interconnect system that is used in liquid crystal displaymanufacturing to make the electrical and mechanical connections from thedriver electronics to the glass substrates of the LCD. ACF bonding isalso used in the smart card industry to connect antenna wires to prelamsubstrates for contactless and dual interface cards. The bonding processuses an ACF tape that has conductive particles in the conductive linesof the tape. During the ACF bonding process, heat and pressure areapplied via a thermode (hot bar). The conductive particles arecompressed between the traces or conductive bumps on the componentsbeing joined and thus provide electrical contact. The conductiveparticles become trapped into a permanent compressed form, with theparticles distributed in a manner to minimize the chance of electricalshorting.

In one embodiment, the ACF bond 105 between the adapter FPC 100 and thesensor layer 56 a is established. Next, the ACF bond 110 between the FPC100 and the prelam substrate 54 is established.

In alternative embodiments, the bond 110 may be conductive solder bumps,such as bumps 60 that connect integrated circuit chip 58 to thesubstrate 54.

As noted above, the FPC 100 is a kind of flexible circuit, which is atechnology for assembling electronic circuits by mounting electronicdevices on flexible plastic substrates, such as a polyimide, PEEK orpolyester film. Flexible circuits can be screen printed silver circuitson polyester. Flexible electronic assemblies may be manufactured usingidentical components used for rigid printed circuit boards, but allowthe board to conform to a desired shape, or to flex during its use.Flexible printed circuits (FPC) are made with a photolithographictechnology. An alternative way of making flexible foil circuits orflexible flat cables (FFCs) is laminating very thin (0.07 mm) copperstrips in between two layers of PET. These PET layers, typically 0.05 mmthick, are coated with an adhesive which is thermosetting, and will beactivated during the lamination process.

Single-sided flexible circuits have a single conductor layer made ofeither a metal or conductive (metal filled) polymer on a flexibledielectric film. Component termination features are accessible only fromone side. Holes may be formed in the base film to allow component leadsto pass through for interconnection, normally by soldering. Single sidedflex circuits can be fabricated with or without such protective coatingsas cover layers or cover coats, however the use of a protective coatingover circuits is the most common practice.

As can be seen from FIG. 3, use of the FPC 100 to electrically connectthe sensor 56 to the substrate 54, which in turn makes the electricalconnection to the integrated circuit chip 58 (and/or other components),allows for formation of a robust prelam layer 152 that can withstand thebending stresses encountered by BSoCs. There are no wire bonds betweenthe sensor 56 and the flexible substrate 54 that are potential points offailure under bending stresses. Further, the connection methodology canbe adapted to mass production techniques, which allows for massproduction of prelam layers for use in mass card productions, asdescribed in more detail below.

Similar to FPC, in one embodiment, connections from the sensor activelayer 56 a to the substrate 54 may use tape automated bonding (TAB)rather than a FPC, such as FPC 100 in FIG. 3. TAB uses a conductivepattern of copper to form interconnections between a chip and asubstrate. The pattern is pre-processed from a continuous copper tape ona dielectric carrier film. The TAB sheet is bonded to gold bumps on thesensor active layer. The leads of the TAB sheet are soldered to thesubstrate using a process called impulse soldering with a tool called athermode. TAB is currently used in liquid crystal displays, electronicwatches and other high volume consumer products.

FIG. 4 shows another embodiment of a prelam layer 252 for use inmanufacturing a BSoC as described above. The prelam layer 252 isidentical in all respects to the prelam layer 152 only the connection ofthe sensor 56 to the flexible substrate 54 is modified. Specifically,the connection arrangement includes a first adapter flexible printedcircuit (FPC) 200 connected to the active side 56 a of the sensor 56 bybonds 205. The adapter FPC 200 is connected to a second adapter FPC 250through bonds 210. The second adapter FPC 250 is connected to theflexible substrate layer 54 through bonds 260. In embodiments, thesecond adapter FPC 250 is a double-sided flexible circuit (FPC), forexample including two conductive layers with an insulating layerbetween, and cover layers or films for the outer layer. The cover filmsare pre-routed to access copper from both sides using conductive throughholes, such as plated thru holes (PTH) or other kind of conductive via.These conductive vias allow electrical connection from one side of theFPC to the other

In embodiments, the bonds 260 are conductive solder bumps. In oneembodiment, the solder bumps 260 are low silver (AG) containinglead-free solder balls, such as Sn/1.0Ag/0.5Cu, commonly called SAC105,or SAC305 (Sn/3.0Ag/0/5Cu) solder balls, with appropriate diameters forthe given application.

In embodiments, both the bonds 210 and 205 are ACF bonds.

In one embodiment, described below in connection with FIGS. 8 and 9, theadapter FPC layer 200 can cover the entire upper surface of the prelam252, except for a window over the active sensor layer 56 a, so as todouble as a cover foil of the smart card.

FIG. 5 shows another embodiment of a prelam layer 352 for use inmanufacturing a BSoC as described above. The prelam layer 352 isidentical in all respects to the prelam layer 152 and 252 only theconnection of the sensor 56 to the flexible substrate 54 is modified andthe orientation of the integrate circuit chip 58 a is flipped respectiveto the integrate circuit chip 58. That is, the active side of theintegrate circuit chip 58 a now faces upwards (in the same direction asthe active side 56 a of the sensor 56), whereas the active side ofintegrate circuit chip 58 faces the flexible substrate 54. Theconnection arrangement includes a single-sided adapter flexible printedcircuit (FPC) 300 connected to the active side of the sensor 56 by bonds305. The adapter FPC 300 is connected to the active side of theintegrate circuit chip 58 a by bonds 310. And the adapter FPC 300 isalso connected to the upper surface of the flexible substrate 54 bybonds 320. In this manner, the adapter FPC 300 connects the sensors 56to the integrate circuit chip 58 a and the integrate circuit chip 58 ato the flexible substrate 54, which can also have other componentsdescribed above in connection with FIG. 1 connected thereto.

In embodiments, the bonds 305, 310 and 320 are ACF bonds.

As with other embodiments, as described below in connection with FIGS. 8and 9, the adapter FPC layer 300 can cover the entire upper surface ofthe prelam 352, except for a window over the active sensor layer 56 a,so as to double as a cover foil of the smart card.

FIG. 6 shows another embodiment of a prelam layer 752 for use inmanufacturing a BSoC as described above. As with prelam layers 152 and252, the integrate circuit chip 58 b is oriented with its active sidefacing the substrate 54, allowing for the integrate circuit chip 58 b tohave conductive solder bump bonds 60 to the substrate 54. The integratecircuit chip 58 b has one or more conductive through silicon vias (TSV)that allow for electrical connections between the two sides of theintegrate circuit chip 58 b. Of course, the active side of the integratecircuit chip 58 b could also face upwards, with the TSVs connecting thatactive layer to leads on the opposite side of the integrate circuit chip58 b that are coupled directly to the substrate 54. In this embodimentthe connection arrangement includes a single-sided adapter flexibleprinted circuit (FPC) 700 connected to the active side of the sensor 56by bonds 705. The adapter FPC 700 is connected to the active side of topside of integrate circuit chip 58 b by bonds 710. In this manner, theadapter FPC 700 connects the sensors 56 directly to the integratecircuit chip 58 b, which is also directly connected to the flexiblesubstrate 54, which can also have other components described above inconnection with FIG. 1 connected thereto. In embodiments, the integratedcircuit chip 58 b is an image capture ASIC.

In embodiments, the bonds 705 and 710 are ACF bonds.

As with other embodiments, as described below in connection with FIGS. 8and 9, the adapter FPC layer 700 can extend to cover the entire uppersurface of the prelam 752, except for a window over the active sensorlayer 56 a, so as to double as a cover foil of the smart card.

FIG. 7 illustrates a cross-sectional view of an embodiment of adouble-sided adapter flexible printed circuit (FPC) 400. The FPC 400includes an insulating layer 402, such as a polyimide layer. Conductivelayers 404 are formed on either side of the insulating layer. Theselayers may, for example, be copper foil layers. Through holes 406 areformed through the insulating layer 402 to allow for electricalconnections between the conductive layers 404. Optional upper and lowerinsulating coverlay layers 408 a, 408 b are formed over the conductivelayers 404. Upper and lower connection areas 410 a, 410 b are providedfor making electrical connections to the conductive layers 404. Theseareas can be used for the solder or ACF bonds discussed above. It shouldbe understood that a single-sided FPC may only have one conductive layer404 and one coverlay layer (e.g., layer 408 a or 408 b) and would notrequire through holes 406.

In one embodiment, the flexible fingerprint sensor 56 is provided withconductive through vias to allow for sensor contacts to be placed on theunderside of sensor substrate 56 b, i.e., on the side opposite of activelayer 56 a. This allows the sensor to be bonded directly onto flexiblesubstrate 54 of the prelam 52, such as by solder ball connection or ACFbonding.

FIG. 8 illustrates a prelam precursor sheet 500. The prelam precursorsheet 500 includes a flexible printed circuit substrate 502 (forexample, corresponding to substrate 54 discussed above) and a pluralityof fingerprint sensors 504 (for example, corresponding to sensor 56discussed above) disposed on the substrate 502. Alignment marks 508denote the boundaries of the sensor active area. Other components, suchas integrate circuit chip 506 (for example, corresponding to integratecircuit chip 58 discussed above) are also disposed on the substrate 502.These components can be arranged on the substrate 502 in a grid withinareas 510 corresponding generally to the size and shape of a standardsmart card (e.g., 85 mm×54 mm).

FIG. 9 shows an adapter FPC sheet 600 (corresponding to, for example,FPC 100, 200, 300 or 700 described above) overlaid on the layer 500 ofFIG. 8. Windows 602 are precut or preformed in the sheet 600 to allowfor exposure of the fingerprint sensors 504 underneath. The adapter FPCsheet 600 overlaps the sensors 504 and is electrically coupled to theactive area of the sensors 504 by, for example, ACF bond, andelectrically coupled to the substrate 502 and/or to the integratecircuit chip 506 via ACF bond and/or conductive solder ball bond asdiscussed above in connection with FIGS. 3 and 5. In the embodiment ofFIG. 4, the layer 600 would be bonded to a second adapter FPC, such asadapter FPC 250.

After electrically bonding the FPC layer 600 to the prelam precursorsheet 500, the assembly (500, 600) can be laminated (using heat and/orpressure) with one or more additional layers (such as described above inconnection with FIG. 2) and cut into individual BSoC cards. Inembodiments, the FPC layer 600 doubles as the, or one of the, toplamination layers. In embodiments, heat and/or pressure is applied afterthe electrical bonding to form a physical bond between the precursorsheet 500 and the FPC layer 600. Alternatively, the physical bond may becreated during the electrical bonding step.

Alignment marks 508 can be provided on the substrate 502 and/or adaptersheet 600 to allow for proper alignment between the sensors 504 and theFPC sheet 600. Since smart cards are also produced on sheets, the sensorcan be optimized for card production.

While sheet 600 is shown as having a plurality of rows and columns ofwindows 602 and electrical connections (not shown) corresponding toindividual cards, it should be understood that the sheet 600 could beprovided as multiple sheets of individual rows of windows and electricalconnections, or as multiple sheets of individual columns of windows andelectrical connections. For example, assuming an N×M grid of card areas510 on prelam precursor sheet 500, sheet 600 could be provided as asingle sheet of N×M elements, or multiple sheets of any combination ofrows and columns sufficient to provide N×M elements, i.e., in whateverform and number facilitates efficient manufacturing and proper alignmentand electrical connection of the sheet(s) 600 to precursor sheet 500.

Although the invention has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly to include other variants and embodiments ofthe invention that may be made by those skilled in the art withoutdeparting from the scope and range of equivalents of the invention.

What is claimed is:
 1. A prelam layer for use in forming a laminated card, comprising: a flexible circuit substrate; a fingerprint sensor disposed on the flexible circuit substrate, the fingerprint sensor having upper and bottom surfaces, the bottom surface of the fingerprint sensor being disposed on said substrate, an active layer of the fingerprint sensor disposed towards the upper surface of the fingerprint sensor; a first integrated circuit chip disposed on said substrate and having at least one lead electrically connected to the flexible circuit substrate; and an adapter flexible circuit electrically bonded to the active layer at the upper surface of the fingerprint sensor, wherein the integrated circuit chip is adapted to communicate with the fingerprint sensor through the adapter flexible circuit.
 2. The prelam layer of claim 1, wherein the adapter flexible circuit is bonded to the active layer of the fingerprint sensor by anisotropic conductive film (ACF) bonding.
 3. The prelam layer of claim 1, wherein the adapter flexible circuit is also electrically bonded to the flexible circuit substrate, wherein the adapter flexible circuit's electrical bond to the flexible circuit substrate couples the first integrated circuit to the fingerprint sensor.
 4. The prelam layer of claim 3, wherein the adapter flexible circuit is bonded to the flexible circuit substrate and to the active layer of the fingerprint sensor by anisotropic film (ACF) bonding.
 5. The prelam layer of claim 3, wherein the adapter flexible circuit is a single-sided adapter flexible printed circuit.
 6. The prelam layer of claim 1, wherein an active layer of the first integrated circuit chip is oriented away from the upper surface of the flexible circuit substrate, and wherein the adapter flexible circuit is electrically bonded to at least one lead of the active layer of the first integrated circuit chip, wherein the first integrated circuit chip and the fingerprint sensor are adapted to directly communicate through the adapter flexible circuit.
 7. The prelam layer of claim 6, wherein the adapter flexible circuit is also electrically bonded to the flexible circuit substrate, thereby electrically connecting the first integrated circuit chip to the flexible circuit substrate.
 8. The prelam layer of claim 7, wherein the wherein the adapter flexible circuit is a single-sided adapter flexible printed circuit.
 9. The prelam layer of claim 8, wherein the adapter flexible circuit is bonded to the fingerprint sensor, the first integrated circuit chip and the flexible circuit substrate by anisotropic film (ACF) bonding.
 10. The prelam layer of claim 1, further comprising a second adapter flexible circuit, wherein the second adapter flexible circuit is a double-sided flexible circuit, wherein an upper side of the second adapter flexible circuit is electrically bonded to a bottom side of the adapter flexible circuit and a bottom side of the second adapter flexible circuit is electrically bonded to the flexible circuit substrate.
 11. The prelam layer of claim 1, wherein the adapter flexible substrate covers the flexible circuit substrate and has a window formed therein overlying the fingerprint sensor.
 12. The prelam layer of claim 1, wherein the first integrated circuit chip comprises an image capture ASIC.
 13. The prelam layer of claim 12, further comprising a microcontroller electrically bonded to the flexible circuit substrate and adapted to communicate with the image capture ASIC through the flexible circuit substrate.
 14. The prelam layer of claim 1, wherein the first integrated circuit chip is a smart card chip controller and the fingerprint sensor is adapted to provide a fingerprint template for comparison by the smart card chip controller.
 15. The prelam layer of claim 1, wherein the fingerprint sensor has a sense area of at least 169 mm².
 16. The prelam layer of claim 1, wherein a first side of the first integrated circuit chip is electrically bonded to the flexible circuit substrate and a second side, opposite the first side, is electrically bonded to the adapter flexible circuit.
 17. The prelam layer of claim 16, wherein the first integrated circuit chip is an image capture ASIC, the prelam layer comprising at least one second integrated circuit chip adapted to communicate with the image capture ASIC through the flexible circuit substrate.
 18. The prelam layer of claim 1, wherein the prelam layer has a total thickness between about 120-450 μm.
 19. A biometric system on card, comprising: at least one bottom lamination layer; a prelam layer disposed over the at least one bottom lamination layer, the prelam layer comprising: a flexible circuit substrate; a fingerprint sensor disposed on the flexible circuit substrate, the fingerprint sensor having upper and bottom surfaces, the bottom surface of the fingerprint sensor disposed on said substrate, an active layer of the fingerprint sensor disposed towards the upper surface of the fingerprint sensor; a first integrated circuit chip disposed on said substrate and having at least one lead electrically connected to the flexible circuit substrate; and an adapter flexible circuit electrically bonded to the active layer at the upper surface of the fingerprint sensor, wherein the first integrated circuit chip is adapted to communicate with the fingerprint sensor through the adapter flexible circuit; and at least one top lamination layer, the top lamination layer having a window formed therein overlying the fingerprint sensor.
 20. The biometric system on card of claim 19, wherein the first integrated circuit chip is a smart card chip controller flip chip bonded to the flexible circuit substrate; wherein the adapter flexible circuit is electrically bonded to the flexible circuit substrate; wherein the adapter flexible circuit's electrical bond to the flexible circuit substrate allows the smart card controller to communicate with the fingerprint sensor through the adapter flexible circuit.
 21. The biometric system on card of claim 19, wherein the first integrated circuit chip has an active side oriented away from an upper surface of the flexible circuit substrate, and wherein the adapter flexible circuit is electrically bonded to at least one lead at the active side of the first integrated circuit chip, whereby the first integrated circuit chip and the fingerprint sensor are adapted to directly communication through the adapter flexible circuit, and wherein the adapter flexible circuit is also bonded to flexible circuit substrate, whereby the first integrated circuit chip is adapted to directly communicate with the flexible circuit substrate through the adapter flexible circuit.
 22. The biometric system on card of claim 19, wherein the least one top lamination layer includes the adapter flexible circuit, the adapter flexible circuit having a window formed therein overlying, the fingerprint sensor.
 23. The biometric system on card of claim 19, wherein the first integrated circuit chip is an image capture ASIC, wherein the prelam layer further comprises at least one second integrated circuit electrically bonded to said flexible circuit, substrate and adapted to communicate with the image capture ASIC through the flexible circuit substrate.
 24. A method of forming prelam layers for use in forming laminated cards, comprising the steps of: providing a flexible circuit substrate sheet having a plurality of areas corresponding to individual cards, each card area having: a fingerprint sensor disposed on the flexible circuit substrate sheet, the fingerprint sensor having upper and bottom surfaces, the bottom surface of the fingerprint sensor disposed on said substrate sheet, an active layer of the fingerprint sensor disposed towards the upper surface of the fingerprint sensor, and a first integrated circuit chip disposed on said flexible circuit substrate sheet; disposing an adapter flexible circuit sheet over the flexible circuit substrate sheet; electrically bonding the adapter flexible circuit sheet to the active layer of each fingerprint sensor; and after the bonding step, cutting the adapter flexible circuit sheet and flexible circuit substrate sheet into a plurality of individual prelam layers, each individual prelam layer comprising one or more of the plurality of areas corresponding to individual cards, each individual prelam layer having a respective flexible circuit substrate and adapter flexible circuit electrically bonded to the flexible circuit substrate, wherein the integrated circuit chip of each individual prelam layer is adapted to communicate with the fingerprint sensor of the each individual prelam layer through the respective adapter flexible circuit.
 25. The method of claim 24, the flexible circuit substrate comprises an array of said plurality of areas corresponding to individual cards, said array comprising a plurality of rows and columns of said areas, wherein the adapter flexible circuit sheet comprises two or more adapter flexible circuit sheets, each of said two or more adapter flexible circuit sheets disposed over a respective subset of the plurality of areas. 